#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(void)
{
    srand(time(NULL));
    int num = rand() % 100;

    printf("num = %d\n", num);
    int flag = 1, i;
    for (i = 2; i <= num / i; i++) {
        if (num % i == 0) {
            flag = 0;
            break;
        }
    }

    if (flag) 
        printf("yes\n");
    else
        printf("no\n");

    return 0;
}

